Research On Vehicle High-precision Positioning Assisted By UAV

Accurate location information is widely used in scenarios such as logistics transportation,lane-level navigation,and aerospace flight.In lane-level navigation,accurate positioning and tracking of vehicles is the most important part,and it is also the most important basic information to realize unmanned driving.Location information can currently be obtained through positioning systems such as Global Navigation Satellite System(GNSS)and Inertial Navigation System(INS).The positioning accuracy of GNSS is generally only 2 to 10 meters,and when the GNSS signal is locally interrupted,the short-term positioning accuracy of the vehicle will drop sharply.Although INS can help vehicles obtain short-term positioning information,it will cause severe position drift over a long period of time.Precise Point Positioning(PPP)technology based on GNSS is an effective tool for high-precision absolute positioning and Visual-Inertial Navigation System(VINS)has also been proven to be able to achieve short-term high-precision relative positioning.Therefore,a new system with short-term precise relative positioning capability is proposed and used to achieve short-term high-precision relative positioning on UAVs and vehicles.The system takes into account that the gravitational acceleration experienced by the vehicle will change due to the difference in latitude,longitude and altitude when driving between cities and the angular velocity generated by the rotation of the earth,so the VINS positioning basis-IMU pre-integration algorithm is redesigned.At the same time,it is proposed to use the information matrix to transmit the error of IMU pre-integration measurement,so that it has better numerical stability in the process of nonlinear optimization.The vehicle experiment shows that it can provide decimeter-level or even centimeter-level high-precision relative positioning when the GNSS signal is interrupted for a short time,and has higher performance than the system before optimization.By coupling the optimized VINS and UAV assisted positioning module,this paper proposes a new system——GVINS that can achieve seamless and high-precision absolute positioning of vehicles.It is a semi-tightly coupled system based on UAV-assisted multi-constellation GNSS PPP and binocular VINS,which can realize the high-precision positioning capability of the vehicle when the GNSS signal is interrupted for a short time or the stability is decreased.The vehicle obtains high-precision positioning information through its own GNSS receiver,short-term precise relative positioning module,radar system and communication with drones flying close to it.The vehicle experiment shows that the absolute positioning accuracy of GVINS in a complex driving environment is decimeter-level,which is higher and more stable than other systems,and has a lower cost than the current lane-level navigation system.The two new systems proposed in this paper can realize short-term decimeter-level precise positioning of UAVs and vehicles,and seamless decimeter-level high-precision positioning of vehicles,laying the foundation for achieving higher-precision vehicle positioning.